Excessive Use of Unsharp Masking

In the following sets of images, the same enhancements were made to the two original images
(A). First, A was stretched to create B, then unsharp masking was done to create C and D,
with a greater amount of unsharp masking done to D. By the time we reach D, unsharp masking
is clearly becoming excessive -- a few stars in the M51 image have dark centers; Einstein's
face is severely distorted.